Systems, devices, and methods for calibration of beam profilers

ABSTRACT

Embodiments generally describe systems, devices, and methods for focusing and calibrating beam profilers. A test object is provided that may include an internal housing rotatable within an external housing. The internal housing may house a light source, a collimator, a filter, and/or a diffuser. A plate may be mounted to the internal housing and may include a plurality of markings. In some embodiments, to focus a beam profiler, the test object may be positioned adjacent the converter plate of a beam profiler. Marker images may be captured and a focus quality may be assessed therefrom. A position of the converter, objective, and/or camera of the beam profiler may be adjusted based on the focus quality. To calibrate, images of the markings in several rotational positions may be captured and used for calibration. The markings may be rotated to several positions by rotating the internal housing relative to the external housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/808,869 filed Jul. 24, 2015, which claims the benefit of U.S.Provisional Application 62/029,164 filed Jul. 25, 2014, the disclosuresof both of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to beam profiler systems andmore particularly to systems and methods for focusing and geometricallycalibrating a beam profiler.

A UV light beam profiler is a metrological imaging tool fordetermination of geometrical parameters of a beam profile, such as,size, position, uniformity, shape, and others. It may be used inmilitary, medical, and commercial applications where precise control ofUV light beam parameters is desired. Like other metrological devices,the beam profiler should be calibrated every time after assembly, repair(e.g., component replacement or the like), alignment, realignment, andfor verification sake. This calibration requirement may be costly, timeintensive, or not readily possible if the beam profiler cannot be easilyremoved from the field or an integrated system. Additionally, for somebeam profilers to work properly, the beam profiler should be focusedproperly.

BRIEF SUMMARY OF THE INVENTION

The terms “invention,” “the invention,” “this invention” and “thepresent invention” used in this patent are intended to refer broadly toall of the subject matter of this patent and the patent claims below.Statements containing these terms should be understood not to limit thesubject matter described herein or to limit the meaning or scope of thepatent claims below. Embodiments of the invention covered by this patentare defined by the claims below, not this summary. This summary is ahigh-level overview of various aspects of the invention and introducessome of the concepts that are further described in the DetailedDescription section below. This summary is not intended to identify keyor essential features of the claimed subject matter, nor is it intendedto be used in isolation to determine the scope of the claimed subjectmatter. The subject matter should be understood by reference toappropriate portions of the entire specification of this patent, any orall drawings and each claim.

There is a need for a tool that can be used for beam profiler focusingand focus verification. Additionally, it may be advantageous if the toolcan perform geometrical calibration of a beam profiler in the fieldwithout having to remove the beam profiler from the host system. Such atool may avoid the need for beam profiler removal from a host system andbeam profiler shipping to a manufacturer for calibration. In someembodiments, it may be advantageous if the tool is compact andinexpensive and can be used anywhere the beam profiler is installed.

Accordingly, in some embodiments of the present invention, a focusingand/or calibration tool is provided. The focusing or geometriccalibration test object may be used with a beam profiler, for example.In some embodiments, the object may include an external housing and aninternal housing rotatably mounted within the external housing androtatable relative to the external housing about an internal housingaxis. The test object may further include a light source housed withinthe internal housing and a plate coupled with the internal housing andtransverse to the internal housing axis. The plate may include aplurality of markings on the plate.

In some embodiments, the test object may further include a lightdiffuser housed in the internal housing and positioned between the lightsource and the plate. The diffuser may be configured to disperse lightfrom the light source across the markings on the plate.

Optionally, the light source may be configured to output light in abroad spectral range and the test object may also include a bandpassfilter housed in the internal housing and positioned between the lightsource and the plate. The bandpass filter may be configured toselectively transmit light from the light source in a particular rangeof wavelengths.

In some embodiments, a collimating lens may be positioned between thelight source and the plate. The collimating lens may be configured tocollimate the light emitted by the light source.

Optionally, the light source may be configured to output light in anarrow bandwidth. In such an embodiment, the test object may not includea bandpass filter.

In some embodiments, the plate may be positioned at a first end of theinternal housing. An outer face of the plate may be even with a firstend of the external housing.

A second end of the internal housing opposite the first end of theinternal housing may include one or more indicia. A second end of theexternal housing opposite the first end of the external housing may alsohave one or more indicia. The indicia on the second end of the internalhousing and the indicia on the second end of the external housing maycooperate to provide rotation information (e.g., a degree of rotation)between the internal housing and the external housing.

In some embodiments, the plurality of markings may be separated by aknown distance. The plurality of markings may be a repeated bar pattern.The repeated bar pattern may include major bars and minor barsindicating different units of length.

Optionally, the plurality of markings on the plate may be a resolutiontest chart.

In some embodiments, the external housing and the internal housingcomprise cylindrical housings.

In further embodiments, a beam profiler system may be provided thatincludes a UV-to-visible converter plate. The UV-to-visible converterplate may be configured to emit fluorescing light when excited by UVradiation. The profiler may further include an image sensor and a lensfor imaging a profile of the fluorescing light from the UV-to-visibleconverter onto the image sensor. The UV-to-visible converter plate andthe lens may be moveable relative to the image sensor.

The beam profiler system may further include a focusing and geometriccalibration test object for use with the beam profiler. The test objectmay include an external housing and an internal housing rotatablymounted within the external housing. The internal housing may berotatable relative to the external housing about an internal housingaxis. A light source may be provided and housed within the internalhousing. A plate may be coupled with the internal housing and transverseto the internal housing axis and a plurality of markings may be on theplate.

The beam profiler may further include a filter positioned between theUV-to-visible converter plate and the image sensor. The filter may beconfigured to selectively transmit light to the image sensor.

Optionally the test object may include a light diffuser, and acollimating lens housed in the internal housing and positioned betweenthe light source and the plate. The diffuser may be configured todisperse light from the light source across the markings on the plate,and the collimating lens may be configured to collimate the lightemitted by the light source.

The light source may be configured to output light in a broad spectralrange. The test object may include a bandpass filter configured toselectively transmit light from the light source in a particular rangeof wavelengths.

Optionally the diffuser may be positioned between the plate and thebandpass filter. The bandpass filter may be positioned between thediffuser and the collimator. The collimator may be positioned betweenthe light source and the bandpass filter.

In some embodiments, the light source may be configured to output lightin a narrow bandwidth and the test object may not include a bandpassfilter.

The lens and the image sensor of the beam profiler may be along a singleaxis with the converter plate of the beam profiler. The lens and theimage sensor of the beam profiler may measure light fluoresced from asurface of the converter plate.

The lens and the converter plate may be fixed together to form alens-converter plate assembly and the lens-converter plate assembly maymove relative to the image sensor of the beam profiler for focusing thebeam profiler.

In further aspects, a method of focusing and/or calibrating a beamprofiler using a test object is provided. The test object may include anexternal housing, an internal housing rotatably mounted within theexternal housing and rotatable relative to the external housing about aninternal housing axis, a light source housed within the internalhousing, an plate coupled with the internal housing and transverse tothe internal housing axis, and a plurality of markings on the plate. Themethod may include (a) positioning the plate of the test object adjacentto a UV-to-visible converter plate of the beam profiler; (b) imaging theplurality of markings on the plate of the test object with the beamprofiler; (c) determining a focus quality of the image of the pluralityof markings; and (d) adjusting a distance between the UV-to-visibleconverter plate of the beam profiler and an objective lens of the beamprofiler.

The method may include repeating steps (b)-(d) until a desired focus ofthe beam profiler is obtained.

Optionally, the method may include energizing the light source of thetest object prior to imaging the plurality of markings on the plate ofthe test object.

The method may further include: (e) imaging the plurality of markings onthe plate of the test object with the beam profiler with the pluralityof markings at a first position; (f) rotating the internal housingrelative to the external housing by a rotational amount to rotate theplurality of markings on the plate to a rotated position; (g) imagingthe plurality of markings on the plate at the rotated position with thebeam profiler; and (h) geometrically calibrating the beam profiler basedon the image of the test object at the first position, the image of thetest object at the rotated position, and the rotational amount.

Optionally, the method may include repeating steps (f)-(g) so as toprovide a plurality of images of the test object at various rotatedpositions. A calibration of the beam profiler may be based on the imageof the test object at the first position, the plurality of images of thetest object at various rotated positions, and the rotational amounts.

In further aspects of the invention, a method of focusing and/orcalibrating a beam profiler using a test object is provided. The methodmay include positioning the plate of the test object adjacent to aUV-to-visible converter plate of the beam profiler and imaging theplurality of markings on the plate of the test object at a firstorientation with the beam profiler. The method may further includerotating the internal housing relative to the external housing by arotational amount to rotate the plurality of markings on the plate to arotated position and imaging the plurality of markings on the plate ofthe test object at the rotated position with the beam profiler. The beamprofiler may be geometrically calibrated based on the image of theplurality of markings at the first orientation, the image of theplurality of markings at the rotated position, and the rotationalamount. In some embodiments, the method may further include energizingthe light source of the test object prior to imaging the plurality ofmarkings on the plate of the test object.

In further aspects of the invention, a calibration and/or focusing toolfor use with a laser eye surgery system is provided. The laser eyesurgery system may have a UV laser, a beam splitter, and a beam fluenceprofiler having a camera and a fluorescent plate. The tool may include ahousing mountable to the laser surgery system and a plate havingreference markings for identification of locations across twodimensions. The plate may be supported by the housing so as to beadjacent the fluorescent plate of the beam fluence profiler when thehousing is mounted to the system such that the markings are imaged bythe camera.

In further aspects, a system for focusing a beam profiler using a testobject is provided. The system may include a processing device and anon-transitory computer-readable medium accessible by the processingdevice. The processing device may be configured to execute logicembodied in the non-transitory computer-readable medium and therebyperform operations including (a) imaging the plurality of markings onthe plate of the test object with the beam profiler at a first positionwhen the plate of the test object is adjacent to a UV-to-visibleconverter plate of the beam profiler; (b) determining a focus quality ofthe image of the plurality of markings; (c) outputting a signalcorresponding the determined focus quality of the image of the pluralityof markings to an operator, the signal being indicative of a need toadjust a distance between the UV-to-visible converter plate of the beamprofiler and an objective lens of the beam profiler; (d) receiving inputrelated to a rotational amount in which the internal housing is rotatedrelative to the external housing to rotate the plurality of markings onthe plate to a rotated position; (e) imaging the plurality of markingson the plate at the rotated position with the beam profiler; and (f)geometrically calibrating the beam profiler based on the image of thetest object at the first position, the image of the test object at therotated position, and the input related to the rotational amount.

The invention will be better understood upon reading the followingdescription and examining the figures which accompany it. These figuresare provided by way of illustration only and are in no way limiting onthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of an exemplary UV light beam profiler;

FIG. 2 illustrates an isometric view of the exemplary UV light beamprofiler in FIG. 1;

FIG. 3 illustrates another exemplary UV light beam profiler;

FIG. 4 illustrates yet another exemplary UV light beam profiler;

FIG. 5 illustrates an exemplary fluence profiler that may incorporateembodiments of a camera-based UV light beam profiler;

FIG. 6 illustrates an exemplary laser system that may benefit fromdirect fluence measurement by a fluence profiler according to someembodiments;

FIG. 7A-7B show an example of UV fluorescent imaging of a laser at 248nm using an exemplary UV light beam profiler;

FIG. 8 illustrates an exploded side view of an exemplary test objectthat may be used for focusing and/or calibration of a UV light beamprofiler;

FIG. 9 illustrates an exploded isometric view of the exemplary testobject illustrated in FIG. 8;

FIG. 10 illustrates exemplary test object of FIG. 8 as assembled;

FIG. 11 illustrates a front view of the exemplary test object of FIG. 8as assembled;

FIG. 12 provides an exemplary work flow for focusing a beam profileraccording to some embodiments of the invention;

FIG. 13 illustrates an exploded view of a coupling of an exemplary testobject with a beam profiler;

FIG. 14 illustrates a front view of the image sensor of the beamprofiler with an image of the plurality of markers of the test object onit;

FIG. 15 provides an exemplary work flow for geometrical calibration of abeam profiler;

FIGS. 16A-16C illustrate a front view of a beam profiler image sensorwith the target image at different rotational positions; and

FIG. 17 is a simplified block diagram of an exemplary computer systemthat may be utilized in embodiments described herein.

DETAILED DESCRIPTION OF THE INVENTION

The subject matter of embodiments of the present invention is describedhere with specificity, but this description is not necessarily intendedto limit the scope of the claims. The claimed subject matter may beembodied in other ways, may include different elements or steps, and maybe used in conjunction with other existing or future technologies. Thisdescription should not be interpreted as implying any particular orderor arrangement among or between various steps or elements except whenthe order of individual steps or arrangement of elements is explicitlydescribed.

FIG. 1 shows a side profile of an exemplary UV light beam profiler 10.FIG. 2 shows an isometric view of the exemplary UV light beam profiler10. UV light beam profiler 10 may include a UV-to-visible lightconverter 12, objective lens 14, filter 16, and an image sensor (orcamera) 18. The components may be housed together in a UV light beamprofiler housing (not shown). The objective lens 14 and the filter 16may be positioned between the converter 12 and the camera 18. In someembodiments the filter 16 is positioned between the objective lens 14and the camera 18.

The UV light beam profiler 10 may work as follows. When the UV lightunder assessment hits the converter 12, it induces fluorescent visiblelight with the profile that replicates the original profile of the UVlight beam. The profile of fluorescent light may be imaged by theobjective lens 14 onto the camera 18. Filter 16 may be used to transmitthe light with the wavelength of fluorescent light and block the lightwith other wavelengths. Camera 18 may be used to convert the image ofthe fluorescent light profile into an electrical signal that is recordedfor further analysis.

The principles of fluorescence imaging are that a UV beam impinges ontofluorescing crystal. The crystal fluoresces in visible wavelengths,proportional to the UV energy in the beam. Then the visible fluorescencemay be imaged with a CCD camera and a normal imaging lens. Both thecrystal and the glass lens block UV scattered light so that only visiblelight may be imaged. There are many crystalline materials that fluorescein the visible in response to UV stimulation. A typical non-crystallinematerial is Cerium doped glass, which may be inexpensive to use.

In some embodiments, the beam profiler 10 may be a fixed-focus camerabased device—the focus may be set as part of the assembly process. Thefocusing may be a manual operation in which an operator sets and securesthe focus of each individual unit. Typically, setting the focus requireshigh-precision positioning of the beam profiler's converter 12 andobjective lens 14 relative to the image sensor 18. Conventional beamprofilers may include high-precision structural features that facilitatesetting the proper focus. In some embodiments, the high-precisionfeatures may be a converter 12 and objective 14 assembly that attachesto the camera housing with screw threads. The threaded attachment mayprovide a mechanism for positioning the focal point on the image sensor,and may maintain planarity between the converter 12, objective lens 14,and image sensor 18. During the assembly of a beam profiler 10, anoperator may thread the converter/objective assembly onto the camerahousing until a desired focus is achieved. Thereafter, the operator mayfix the threaded converter/objective assembly positioning usingadhesives, for example. Thus, screw threads for positioning a converter12/objective 14 assembly on a camera housing may provide a mechanism forachieving a high accuracy/high precision positioning of theconverter/objective without the use of high precision assemblyinstruments.

FIG. 3 illustrates another exemplary UV light beam profiler 20. UV lightbeam profiler 20 includes a fluorescent plate 22, an imaging lens 24,and an image sensor 26 (CCD). The setup of FIG. 3 provides a slightlyoff-axis reflection measurement where the visible light is imaged fromthe same side as the incident beam. As illustrated in FIG. 3, this setupmay position the imaging lens 24 and the image sensor 26 assembly to beon the same side as the input beam 28. In this setup, UV input beam 28impinges on the fluorescing plate 22. The fluorescing/visible light 29is then imaged by the lens 24 and CCD 26 assembly from a front surface23 of the fluorescing plate 22. In some embodiments, a filter may beused to block UV light from the imaging sensor 26.

FIG. 4 illustrates another exemplary UV light beam profiler 30. In thesetup of FIG. 4, the fluorescing plate 32 may be at 45° between theincident beam 28 and the imaging lens 34 and CCD sensor 36 assembly.This setup allows the lens 34 and the CCD 36 assembly to image thefluorescing light 29 at 90° relative to the incident beam 28.

FIG. 5 illustrates an exemplary fluence profiler 40 that may incorporateembodiments of a camera-based UV light beam profiler. Exemplary fluenceprofiler 40 works as follows. A fraction of a UV beam 42 may be splitinto two parts 44, 46 by beam splitter 48. The first part 44 of the beam42 may be analyzed by a camera-based device 50 (e.g., UV light beamprofiler 10, 20, 30 or the like) and the second part 46 of the beam 42may be analyzed by an ultraviolet radiation sensor 52 by measuring thetotal energy of UV radiation (TB).

With the profile and energy measurements from the camera-based device 50and the ultraviolet radiation sensor 52, the fluence profile may becalculated by associating the portion of the total energy to pixels ofthe beam profile depending on the pixel weight. Embodiments of thefluence profiler 40 may provide real-time detection of beam shape, beamsize, and/or beam position. The real-time detection may be advantageous,for example, during refractive surgery as it allows for monitoring of atreatment in real-time and if needed, revision of the treatment inreal-time when deviations from a desired treatment are calculated.Further, many embodiments of the fluence profiler 40 may have little orno moving parts. And, preferably, the fluence profiler 40 may beresistant to ambient light errors when making beam size, shape, and/orposition measurements, etc.

Camera-based device 50 may comprise a housing 412 for housing aUV-to-visible converter 414, an objective lens 416, and an image sensor418. The first part 44 of the beam 42 falls on the UV-to-visibleconverter 414 and excites fluorescent light 430 in the visible range.Florescent light 430 propagates in all directions including directionstoward the back surface 415 of the converter plate 414. The lightemitted from the back surface 415 of the converter 414 is imaged by theobjective lens 416 onto image sensor 418. The image sensors 418 isconfigured to detect the profile (shape) of florescent light that isproportional to the beam profile of the excitation UV radiation.

While illustrated and described with an in-line configuration andwithout a filter, It should be understood that UV light beam profiler10, 20, 30 or the like may be used in many embodiments.

Ultraviolet radiation sensor 52 may comprise a housing 422 (e.g. 122 onFIG. 5) for housing a UV-to-visible converter 414, a light blocker 424,a conical mirror 426, and a detector 428. The second part 46 of the beam42 falls on the UV-to-visible converter plate 414 and excitesfluorescent light 430 in the visible range. Fluorescent light 430propagates in all directions including directions toward the edge of theconverter plate 414. Light blocker 424 may be positioned adjacent to aback surface 415 of converter plate 414 and may be configured to blockambient light from reaching detector 428. The light 430 emitted from theedge of the converter plate 414 is redirected with a conical mirror 426toward detector 428, thereby bypassing light blocker 424. The detector428 may be configured to detect the energy of fluorescent light 430 thatis proportional to the total energy of the excitation UV radiation.

FIG. 6 illustrates an exemplary laser system that may benefit fromdirect fluence measurement by a fluence profiler 40 according to someembodiments. As illustrated in FIG. 6, a laser beam 510 from a lasersystem 500 may be sent through a beam dividing element (BDE) 505 suchthat a fraction 512 of the beam 510 can be sent to the fluence profiler40 along optical path 2 (OP2). The bulk 514 of the original laser beam510 may go through optical path 1 (OP1) to be delivered onto thepatient's cornea 550.

While laser system 500 is illustrated as an ophthalmic surgery lasersystem it should be understood that many methods and devices disclosedherein may be applicable with other laser systems where it is desirableto measure beam energy, fluence, and profile combined or separately.

An example of UV fluorescent imaging of a laser at 248 nm is provided inFIGS. 7A-7B. A rectangular aperture was used to pick off a portion ofthe beam. FIG. 7A is an initial measurement and FIG. 7B is a subsequentmeasurement after adjustments were made to the laser and optics toprovide a more uniform intensity.

As mentioned above, embodiments of the fluence profiler 40 may providereal-time detection of beam energy, beam shape, beam size, and/or beamposition and such real-time detection may have many advantageous. Forexample, during refractive surgery, it may allow for monitoring of atreatment in real-time and if needed, revision of the treatment inreal-time when deviations from a desired treatment are calculated.However, for beam profilers (e.g., profiler 10, 20, 30, 50, or the like)to work properly (and consequently a fluence profiler 40 that comprisesthe UV beam profiler), the converter, objective, and camera should bealigned or focused in such a way that the converter is located at theobject plane OP and the camera is located at the image plane IP of theobjective lens (see FIG. 1). If converter or camera are out of object orimage plane, respectively, the data acquired by the beam profiler may bemisinterpreted.

Accordingly, there is a need for a tool that can be used for beamprofiler focusing and focus verification. Additionally, the beamprofiler should be calibrated frequently (e.g., after assembly, repair,alignment, realignment, for verification purposes, etc.). This tool maybe applicable to any beam profiler that uses a converter plate toconvert invisible radiation into visible radiation for further detectionand analysis.

FIG. 8 illustrates an exploded side view of an exemplary test object 100that may be used for focusing and/or calibration of a UV light beamprofiler. FIG. 9 illustrates an exploded isometric view of the exemplarytest object 100. FIG. 10 illustrates exemplary test object 100 asassembled. FIG. 11 illustrates a front view of exemplary test object100. Test object 100 includes an internal housing 102 housed withinexternal housing 104. Internal housing 102 may be rotatable relative toexternal housing 104 about internal housing 102 axis 103. Internalhousing 102 may house a light source 106, a collimator 108, a bandpassfilter 110, and a diffuser 112. A plate 114 may be positioned at an end102 a of internal housing 102 and mounted thereto. The plate 114 mayinclude a plurality of markings 116.

The external housing 104 includes an opening for receiving the internalhousing 102. In some embodiments, the opening of external housing 104may be a generally cylindrical shape for receiving a cylindricallyshaped internal housing 102. While illustrated as generally having acylindrical body, it should be understood that other configurations arepossible. An external body 104 with a cylindrical configuration mayhowever provide for a more compact design.

The internal housing 102 may comprise a generally cylindrical body thatcorresponds to the opening of external housing 104 and may be rotatableabout internal housing axis 103 within external housing 104. Thecylindrical body may include an end 102 b opposite end 102 a. The end102 b may have a raised surface 118 extending laterally or transversefrom axis 103. The raise surface 118 may extend a distance approximatelyequal to a thickness of a wall of external housing 104 so that wheninternal housing 102 is housed therein, the raised surface 118 ofinternal housing 102 may be generally flush with an outer surface ofexternal housing 104. Additionally, the raised surface 118 of internalhousing 102 may incorporate indicia 120 that cooperate with indicia 122on the outer surface of the external housing 104 to provide rotationalrelationship information between the internal housing 102 and theexternal housing 104.

In the illustrated embodiment, the external housing 104 includes aplurality of indicia 122 at the end proximate to end 102 b of internalhousing 102. The plurality of indicia 122 on external housing 104include major and minor indicia, and the end 102 b of internal housing102 includes a single indicia 120. While the exemplary embodiment 100includes a plurality of indicia 122 on the external housing 104 and asingle indicia 120 on the raised surface 118 of internal housing 102, itshould be understood that other configurations are possible. Forexample, the external housing 104 may have a single indicia thatcooperates with a plurality of indicia on internal housing 102.

Light source 106 may be configured to emit light in the broad spectralrange (e.g., 350-1000 nm). For example, LEDs, OLEDS, or othernon-coherent light sources. The light from the light source 106 may becollimated by collimator 108. The bandpass filter 110 may be a narrowband filter that may transmit the light with the wavelength of thefluorescent light of the beam profiler 10 while blocking the light withother wavelengths. As an example, a Bandpass Colored Glass Filter FGV9from Thorlabs™ may be used if converter generates the fluorescent lightin the range 485-565 nm. The diffuser 112 may evenly disperse the lightacross plane 114 and the plurality of markings 116. The plurality ofmarkings 116 may be a repeated bar pattern with known parameters and maybe designed for transmission of light (e.g., transparent). As anexample, a USAF 1951 resolution test pattern may be used or any otherresolution pattern, depending on the accuracy requirements for focusingand calibration. Plate 114 may be opaque such that light exiting thetest object 100 is in the desired pattern 116.

In some embodiments, a bandpass filter 110 may not be needed. Forexample, in some embodiments a light source 106 may be configured toemit light in a narrow bandwidth. As an example, an Ultra Bright Red LEDLED630E from Thorlabs™ may be used if converter generates thefluorescent light in the range (639±10) nm. Other coherent light sourcesmay be used in some embodiments. In such an embodiment, test object 100may not need a bandpass filter 110 to transmit particular wavelengths oflight.

The test object 100 may be used for both focusing and calibration of aUV light beam profiler 10. Additionally, the test object 100 may be usedin the field where the beam profiler 10 is integrated within a hostsystem and cannot be removed from the system.

FIG. 12 provides an exemplary work flow 200 for focusing a beamprofiler. At step 202, the test object may be placed in close proximityto the beam profiler in such a way that the plurality of markings (e.g.,a repeated bar pattern) of the test object 100 touches the converter ofa beam profiler. At step 204, an image of the test object 100 may becaptured with the beam profiler. A focus quality of the captured imagemay be determined 206. A signal related to the focus quality of theimage may be output 208 to an operator. At step 210 a determination maybe made, based on the focus quality of the image and/or the outputsignal, as to whether the position of the converter, objective, and/orcamera should be adjusted to improve a focus quality of subsequentlycaptured images. At step 212, adjustments to a positioning of theconverter, objective, and/or camera are made. Steps 204-212 may berepeated until a desired focus quality is achieved or to verify a focusof the beam profiler.

FIG. 13 illustrates an exploded view of an assembly of an exemplary testobject 100 with beam profiler 10. FIG. 14 illustrates a front view ofthe image sensor 18 of the beam profiler 10 with an image of theplurality of markers of the test object 100 on it. It should beunderstood that test object 100 may be used for focusing and/orcalibrating other beam profilers. The illustrated us with beam profiler10 is exemplary and non-limiting.

Focus quality may be assessed in many ways. One of them is based onmeasuring the contrast within a sensor field. The intensity differencebetween adjacent pixels of the sensor naturally increases with correctimage focus. The optical system can thereby be adjusted until themaximum contrast is detected.

In some embodiments, during beam profiler assembly, the converter andobjective may be rigidly fixed together so that the converter ispositioned at the object plane of the objective. The converter andobjective assembly may then be moved relative to the image sensor toadjust the focus of the beam profiler. Optionally, the converter,objective, and/or camera sensor may be individually moved to achieve thedesired beam profiler focus. After a desired focus is achieved, aposition of the converter, objective, and/or camera may be rigidlyfixed.

In many embodiments, the image sensors of beam profilers may express theimage coordinates in pixels. While the focusing provides a desired imagequality of the beam profile focused onto the image sensor, a calibrationprocedure specifies the relationship and establishes the conversionfactors between pixels and the physical object units, for example,millimeters. The calibration provides a mapping from object space (wherefluorescent beam profile is generated) to image space (where fluorescentbeam profile is recorded). Knowing the value of these conversion factorsis important for accurate beam profile parameter determination. Accuratefocusing and calibration of the beam profilers may significantly impactquantitative measurements (e.g., size, shape, uniformity, or the like)extracted from the images. The geometric calibration of a beam profilermay be performed by the methods described below.

FIG. 15 provides an exemplary work flow 300 for geometrical calibrationof a beam profiler. At step 302, the test object 100 may be placed inclose proximity to the beam profiler in such a way that the plurality ofmarkings (e.g., a repeated bar pattern) of the test object 100 touchesthe converter of a beam profiler. In some embodiments, if thecalibration is being performed after a focusing of the beam profiler,the test object 100 may be left in place.

An image of the plurality of markers of the test object may then becaptured 304. The plurality of markers of the test object may be rotatedto another position by rotating the internal housing relative to theexternal housing of the test object 306. An image of the plurality ofmarkers of the test object at the rotated position may then be captured308. Steps 306-308 may be repeated to capture images of the target withthe beam profiler for several distinct positions of the target.Thereafter, the calibration for the beam profiler may then be calculated310 based on the plurality of images of the target.

FIGS. 16A-16C illustrate a front view of a beam profiler image sensorwith the target image at different rotational positions. FIG. 16A is animage for the horizontal orientation of the image. FIG. 16B and FIG. 16Care images for the angle orientation of the target.

Calibration may be determined by a scale factor measured in pixel permm—[pix/mm]. A scale factor relates the physical dimensions andlocations of the laser spot at a converter plate to the correspondingdimensions and locations on a CCD image. In a general case, the shape ofthe pixel is rectangular that requires measuring two scale factors alongdirections of the pixel's sides which in turn, requires detecting targetimage at different rotational positions. In the case of a square pixelshape, there may be only one scale factor that may be measured bydetecting a single target image.

One or more computing devices may be adapted to provide desiredfunctionality by accessing software instructions rendered in acomputer-readable form. When software is used, any suitable programming,scripting, or other type of language or combinations of languages may beused to implement the teachings contained herein. However, software neednot be used exclusively, or at all. For example, some embodiments of themethods and systems set forth herein may also be implemented byhard-wired logic or other circuitry, including but not limited toapplication-specific circuits. Combinations of computer-executedsoftware and hard-wired logic or other circuitry may be suitable aswell.

Embodiments of the methods disclosed herein may be executed by one ormore suitable computing devices. Such system(s) may comprise one or morecomputing devices adapted to perform one or more embodiments of themethods disclosed herein. As noted above, such devices may access one ormore computer-readable media that embody computer-readable instructionswhich, when executed by at least one computer, cause the at least onecomputer to implement one or more embodiments of the methods of thepresent subject matter. Additionally or alternatively, the computingdevice(s) may comprise circuitry that renders the device(s) operative toimplement one or more of the methods of the present subject matter.

Any suitable computer-readable medium or media may be used to implementor practice the presently-disclosed subject matter, including but notlimited to, diskettes, drives, and other magnetic-based storage media,optical storage media, including disks (e.g., CD-ROMS, DVD-ROMS,variants thereof, etc.), flash, RAM, ROM, and other memory devices, andthe like.

To this end, FIG. 17 is a simplified block diagram of an exemplarycomputer system 800 that may be utilized in embodiments describedherein. The computer system 800 typically includes at least oneprocessor 802 which communicates with a number of peripheral devices viaa bus subsystem 804. These peripheral devices may include a storagesubsystem 805, comprising a memory subsystem 806 and a file storagesubsystem 808, user interface input devices 810, user interface outputdevices 812, and a network interface subsystem 814. Network interfacesubsystem 814 provides an interface to a communication network 816 forcommunication with other imaging devices, databases, or the like.

The processor 802 performs the operations of the computer system 800using execution instructions stored in the memory subsystem 806 inconjunction with any data input from an operator. Such data can, forexample, be input through user interface input devices 810, such as thegraphical user interface. Thus, processor 802 can include an executionarea into which execution instructions are loaded from memory. Theseexecution instructions will then cause processor 802 to send commands tothe computer system 800. Although described as a “processor” in thisdisclosure, the functions of the processor may be performed by multipleprocessors in one computer or distributed over several computers.

User interface input devices 810 may include a keyboard, pointingdevices such as a mouse, trackball, touch pad, or graphics tablet, ascanner, foot pedals, a joystick, a touchscreen incorporated into thedisplay, audio input devices such as voice recognition systems,microphones, and other types of input devices. In general, use of theterm “input device” is intended to include a variety of conventional andproprietary devices and ways to input information into the computersystem. Such input devices will often be used to download a computerexecutable code from a computer network or a tangible storage mediaembodying steps or programming instructions for any of the methods ofthe present invention.

User interface output devices 812 may include a display subsystem, aprinter, a fax machine, or non-visual displays such as audio outputdevices. The display subsystem may be a cathode ray tube (CRT), aflat-panel device such as a liquid crystal display (LCD), a projectiondevice, or the like. The display subsystem may also provide non-visualdisplay such as via audio output devices. In general, use of the term“output device” is intended to include a variety of conventional andproprietary devices and ways to output information from the computersystem to a user.

Storage subsystem 805 stores the basic programming and data constructsthat provide the functionality of the various embodiments. For example,database and modules implementing the functionality of embodimentsdescribed herein may be stored in storage subsystem 805. These softwaremodules are generally executed by processor 802. In a distributedenvironment, the software modules may be stored in a memory of aplurality of computer systems and executed by processors of theplurality of computer systems. Storage subsystem 805 typically comprisesmemory subsystem 806 and file storage subsystem 808.

Memory subsystem 806 typically includes a number of memories including amain random access memory (RAM) 818 for storage of instructions and dataduring program execution and a read only memory (ROM) 820 in which fixedinstructions are stored. File storage subsystem 68 provides persistent(non-volatile) storage for program and data files, and may include ahard disk drive, a floppy disk drive along with associated removablemedia, a Compact Digital Read Only Memory (CD-ROM) drive, an opticaldrive, DVD, CD-R, CD-RW, or removable media cartridges or disks. One ormore of the drives may be located at remote locations on other connectedcomputers at other sites coupled to the computer system. The databasesand modules implementing the functionality of the present invention mayalso be stored by file storage subsystem 808.

Bus subsystem 804 provides a mechanism for letting the variouscomponents and subsystems of the computer system communicate with eachother as intended. The various subsystems and components of the computersystem need not be at the same physical location but may be distributedat various locations within a distributed network. Although bussubsystem 804 is shown schematically as a single bus, alternateembodiments of the bus subsystem may utilize multiple busses.

The computer system 800 itself can be of varying types including apersonal computer, a portable computer, a workstation, a computerterminal, a network computer, a module in a display unit, a mainframe,or any other data processing system. Due to the ever-changing nature ofcomputers and networks, the description of the computer system 800depicted in FIG. 30 is intended only as a specific example for purposesof illustrating one embodiment of the present invention. Many otherconfigurations of the computer system are possible having more or fewercomponents than the computer system 800 depicted in FIG. 30.

Different arrangements of the components depicted in the drawings ordescribed above, as well as components and steps not shown or describedare possible. Similarly, some features and sub-combinations are usefuland may be employed without reference to other features andsub-combinations. Embodiments of the invention have been described forillustrative and not restrictive purposes, and alternative embodimentswill become apparent to readers of this patent. Accordingly, the presentinvention is not limited to the embodiments described above or depictedin the drawings, and various embodiments and modifications may be madewithout departing from the scope of the claims below.

What is claimed is:
 1. A beam profiler system comprising: a beamprofiler comprising: a UV-to-visible converter plate configured to emitfluorescing light when excited by UV radiation; and an image sensor;wherein the UV-to-visible converter plate is moveable relative to theimage sensor; and a focusing and geometric calibration test object foruse with the beam profiler comprising: an external housing; an internalhousing rotatably mounted within the external housing and rotatablerelative to the external housing about an internal housing axis; a lightsource housed within the internal housing; a plate coupled with theinternal housing and transverse to the internal housing axis; and aplurality of markings on the plate.
 2. The beam profiler system of claim1, wherein the beam profiler further comprises a filter positionedbetween the UV-to-visible converter plate and the image sensor, andwherein the filter is configured to selectively transmit light to theimage sensor.
 3. The beam profiler system of claim 1 wherein thefocusing and geometric calibration test object further comprises: alight diffuser; and a collimating lens housed in the internal housingand positioned between the light source and the plate, wherein the lightdiffuser is configured to evenly disperse light from the light sourceacross the markings on the plate, and wherein the collimating lens isconfigured to collimate the light emitted by the light source.
 4. Thebeam profiler system of claim 3, wherein the light source is configuredto output light in a broad spectral range, and wherein the test objectfurther comprises a bandpass filter configured to selectively transmitlight from the light source in a particular range of wavelengths.
 5. Thebeam profiler system of claim 4, wherein the diffuser is positionedbetween the plate and the bandpass filter, wherein the bandpass filteris positioned between the light diffuser and the collimating lens, andwherein the collimating lens is positioned between the light source andthe bandpass filter.
 6. The beam profiler system of claim 3, wherein thelight source is configured to output light in a narrow bandwidth, andwherein the test object does not include a bandpass filter.
 7. The beamprofiler system of claim 3, wherein the image sensor of the beamprofiler measures light fluoresced from a surface of the UV-to-visibleconverter plate.
 8. A beam profiler system comprising: a beam profilercomprising: a UV-to-visible converter plate configured to emitfluorescing light when excited by UV radiation; an image sensor; and alens for imaging a profile of the fluorescing light from theUV-to-visible converter onto the image sensor; and a focusing andgeometric calibration test object for use with the beam profilercomprising: an external housing; an internal housing rotatably mountedwithin the external housing and rotatable relative to the externalhousing about an internal housing axis; a light source housed within theinternal housing; a plate coupled with the internal housing andtransverse to the internal housing axis; and a plurality of markings onthe plate.
 9. The beam profiler system of claim 8, wherein the beamprofiler further comprises a filter positioned between the UV-to-visibleconverter plate and the image sensor, and wherein the filter isconfigured to selectively transmit light to the image sensor.
 10. Thebeam profiler system of claim 8 wherein the focusing and geometriccalibration test object further comprises: a light diffuser; and acollimating lens housed in the internal housing and positioned betweenthe light source and the plate, wherein the light diffuser is configuredto evenly disperse light from the light source across the markings onthe plate, and wherein the collimating lens is configured to collimatethe light emitted by the light source.
 11. The beam profiler system ofclaim 10, wherein the light source is configured to output light in abroad spectral range, and wherein the test object further comprises abandpass filter configured to selectively transmit light from the lightsource in a particular range of wavelengths.
 12. The beam profilersystem of claim 11, wherein the diffuser is positioned between the plateand the bandpass filter, wherein the bandpass filter is positionedbetween the light diffuser and the collimating lens, and wherein thecollimating lens is positioned between the light source and the bandpassfilter.
 13. The beam profiler system of claim 8, wherein the lightsource is configured to output light in a narrow bandwidth, and whereinthe test object does not include a bandpass filter.
 14. The beamprofiler system of claim 8, wherein the image sensor of the beamprofiler measures light fluoresced from a surface of the UV-to-visibleconverter plate.
 15. A beam profiler system comprising: a beam profilercomprising: a converter plate configured to emit light when excited bylaser radiation; and an image sensor; and a test object for use with thebeam profiler comprising: a light source; and a plate; wherein the lightsource of the test object, when projected through the plate of the testobject, produces a pattern for imaging at the image sensor of the beamprofiler.
 16. The beam profiler system of claim 15, wherein the beamprofiler further comprises a filter positioned between the converterplate and the image sensor, and wherein the filter is configured toselectively transmit light to the image sensor.
 17. The beam profilersystem of claim 15 wherein the test object further comprises: a lightdiffuser; and a collimating lens positioned between the light source andthe plate, wherein the light diffuser is configured to evenly disperselight from the light source across the plate, and wherein thecollimating lens is configured to collimate the light emitted by thelight source.
 18. The beam profiler system of claim 16, wherein thelight source is configured to output light in a broad spectral range,and wherein the test object further comprises a bandpass filterconfigured to selectively transmit light from the light source in aparticular range of wavelengths.
 19. The beam profiler system of claim18, wherein the diffuser is positioned between the plate and thebandpass filter, wherein the bandpass filter is positioned between thelight diffuser and the collimating lens, and wherein the collimatinglens is positioned between the light source and the bandpass filter. 20.The beam profiler system of claim 15, wherein the light source isconfigured to output light in a narrow bandwidth, and wherein the testobject does not include a bandpass filter.
 21. The beam profiler systemof claim 15, wherein the image sensor of the beam profiler measureslight fluoresced from a surface of the converter plate.